Bellows for immersion cooling

ABSTRACT

A bellows assembly and related methods are described. The bellows assembly can be used in a two-phase immersion cooling system to regulate pressure in a tank&#39;s airspace above a coolant liquid. The bellows assembly can include a flexible container and pressure-release valves located to reduce emissions of coolant liquid vapor into an ambient environment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a bypass continuation of international patentapplication No. PCT/US2023/067056, titled “Bellows for ImmersionCooling,” and filed May 16, 2023.

BACKGROUND

As feature sizes and transistor sizes have decreased for integratedcircuits (ICs), the amount of heat generated by a single chip, such as amicroprocessor, has increased. Chips that once were air cooled haveevolved to chips needing more heat dissipation than can be provided byair alone. In some cases, immersion cooling of chips in a coolant liquidis employed to maintain IC chips at appropriate operating temperatures.

SUMMARY

The present disclosure relates to a bellows assembly that can be usedfor pressure regulation and that allows for gas expansion in two-phaseimmersion cooling systems, and in some instances in single-phaseimmersion cooling systems. The bellows assembly includes a containerhaving at least one flexible, polymeric wall that can deform outwardfrom a center of the bellows and deform inward to change an amount ofvolume enclosed by the container. Hardware elements (such as mountinghardware, pressure-relief vent(s), and/or port(s)) can be mounted on thecontainer. The bellows pressure-relief vent(s) can be arranged to reducean amount of coolant-liquid vapor released from the container during anoverpressure event.

Some implementations relate to a bellows assembly for a two-phaseimmersion cooling system. The bellows assembly can include: a containercomprising a polymer and enclosing a volume, the container having afirst surface spanning a first surface area that encloses the volume,wherein at least a portion of the container is reversibly deformable toincrease and decrease an amount of the volume enclosed by the container;a first wall comprising the polymer and having a second surface spanninga second surface area; a second wall having a third surface spanning athird surface area, the second wall separated from the first wall by atleast a portion of the volume and oriented approximately parallel to thefirst wall when the volume is not under pressure or vacuum, wherein thesecond surface area and the third surface area comprise a majority ofthe first surface area; a third wall extending between and connected tothe first wall and the second wall; at least one port in the third wallto admit gas into the volume and expel the gas from the volume; and atleast one hardware element attached to at least one of the first wall,the second wall, and the third wall to mount the container in anorientation such that at least one of the first wall and the second walldeforms or deform outward from a center of the container withoutexternal hinderance when the volume is under pressure and deforms ordeform inward without external hinderance when the volume is undervacuum.

Some implementations relate to a method of regulating pressure in atwo-phase immersion cooling system. The method can include acts of:receiving gas through a port and into a volume enclosed by a containerof a bellows assembly in response to an increase in pressure of the gas,the container having a first surface spanning a first surface area thatencloses the volume; deforming a first wall of the container in a firstdirection to increase the volume while receiving the gas, wherein thefirst wall comprises a polymer and has a second surface spanning asecond surface area; expelling the gas from the volume in response to adecrease in pressure of the gas; and deforming the first wall of thecontainer in a second direction opposite the first direction to decreasethe volume while expelling the gas. The container can include a secondwall having a third surface spanning a third surface area, the secondwall being separated from the first wall by at least a portion of thevolume and oriented approximately parallel to the first wall when thevolume is not under pressure or vacuum. The second surface area and thethird surface area can comprise a majority of the first surface area.The container can further include a third wall extending between andconnected to the first wall and the second wall, and the bellowsassembly can include at least one hardware element attached to at leastone of the first wall, the second wall, and the third wall to mount thecontainer in an orientation such that at least one of the first wall andthe second wall deforms or deform outward from a center of the containerwithout external hinderance when the volume is under pressure anddeforms or deform inward without external hinderance when the volume isunder vacuum.

Some implementations relate to a two-phase immersion cooling systemcomprising: a tank to contain one or more printed circuit boards havingsemiconductor dies to be cooled during operation of the semiconductordies; coolant liquid within the tank that immerses the one or moreprinted circuit boards; air space within the tank above the coolantliquid; and a bellows assembly fluidically coupled to the air space andforming a normally-closed first volume that includes the air space. Thebellows assembly can include: a container comprising a polymer andenclosing a second volume that is a portion of the first volume, thecontainer having a first surface spanning a first surface area thatencloses the second volume, wherein at least a portion of the containeris reversibly deformable to increase and decrease an amount of thesecond volume enclosed by the container; a first wall comprising thepolymer and having a second surface spanning a second surface area; asecond wall having a third surface spanning a third surface area, thesecond wall separated from the first wall by at least a portion of thesecond volume and oriented approximately parallel to the first wall whenthe first volume is not under pressure or vacuum, wherein the secondsurface area and the third surface area comprise a majority of the firstsurface area; a third wall extending between and connected to the firstwall and the second wall; at least one port in the third wall to admitgas into the second volume from the air space when the first volume isunder pressure and expel the gas from the second volume into the airspace when the first volume is under vacuum; and at least one hardwareelement attached to at least one of the first wall, the second wall, andthe third wall to mount the container in an orientation such that atleast one of the first wall and the second wall deforms or deformoutward from a center of the container without external hinderance whenthe first volume is under pressure and deforms or deform inward withoutexternal hinderance when the first volume is under vacuum.

Some implementations relate to a method of cooling semiconductor dies ina tank of a two-phase immersion cooling system. The method can includeacts of: receiving heat from the semiconductor dies into a coolantliquid within the tank, the coolant liquid filling a portion of the tankbelow an air space occupying a top region of the tank; receiving gasfrom the air space into a volume enclosed by a container of a bellowsassembly in response to an increase in pressure of the gas, wherein thebellows assembly includes a port fluidically coupled to the air spaceand the container has a first surface spanning a first surface area thatencloses the volume; deforming a first wall of the container in a firstdirection to increase the volume while receiving the gas, wherein thefirst wall comprises a polymer and has a second surface spanning asecond surface area; expelling the gas from the volume in response to adecrease in pressure of the gas; and deforming the first wall of thecontainer in a second direction opposite the first direction to decreasethe volume while expelling the gas. The container can include a secondwall having a third surface spanning a third surface area, the secondwall being separated from the first wall by at least a portion of thevolume and oriented approximately parallel to the first wall when thevolume is not under pressure or vacuum. The second surface area and thethird surface area can comprise a majority of the first surface area.The container can further include a third wall extending between andconnected to the first wall and the second wall, and the bellowsassembly can further include at least one hardware element attached toat least one of the first wall, the second wall, and the third wall tomount the container in an orientation such that at least one of thefirst wall and the second wall deforms or deform outward from a centerof the container without external hinderance when the volume is underpressure and deforms or deform inward without external hinderance whenthe volume is under vacuum.

All combinations of the foregoing concepts and additional conceptsdiscussed in greater detail below (provided such concepts are notmutually inconsistent) are part of the inventive subject matterdisclosed herein. In particular, all combinations of subject matterappearing in this disclosure are part of the inventive subject matterdisclosed herein. The terminology used herein that also may appear inany disclosure incorporated by reference should be accorded a meaningmost consistent with the particular concepts disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The skilled artisan will understand that the drawings primarily are forillustrative purposes and are not intended to limit the scope of theinventive subject matter described herein. The drawings are notnecessarily to scale; in some instances, various aspects of theinventive subject matter disclosed herein may be shown exaggerated orenlarged in the drawings to facilitate an understanding of differentfeatures. In the drawings, like reference characters generally refer tolike features (e.g., functionally and/or structurally similar elements).

FIG. 1 depicts a two-phase immersion-cooling system to remove heat fromsemiconductor dies during operation of the semiconductor dies.

FIG. 2A illustrates, with a semi-transparent perspective view, anexample of a bellows assembly that can be used with the immersioncooling system of FIG. 1 .

FIG. 2B depicts an enlarged view (in cross-section) of one example ofmounting hardware elements that can be included in the bellows assemblyof FIG. 2A.

FIG. 2C depicts an additional example of mounting hardware elements thatcan be included in the bellows assembly of FIG. 2A.

FIG. 2D depicts a cross-section of the container, taken at the locationindicated by the dashed line in FIG. 2A.

FIG. 2E depicts deformation of walls of the container of FIG. 2A whenthe pressure of gas within the container increases.

FIG. 2F depicts deformation of walls of the container of FIG. 2A whenthe pressure of gas within the container decreases.

FIG. 3A depicts an example of port components and a vapor barrier thatcan be used with the bellows assembly of FIG. 2A.

FIG. 3B illustrates an example of a port insert that can be used in theassembly of FIG. 3A.

FIG. 3C depicts an additional example of port components and a vaporbarrier that can be used with the bellows assembly of FIG. 2A.

FIG. 3D illustrates an example of an exterior port insert that can beused in the assembly of FIG. 3C.

FIG. 3E illustrates an example of a port in perspective view.

FIG. 4A depicts one arrangement of a heating element that can be used toprovide heat to the bellows assembly of FIG. 2A.

FIG. 4B depicts an additional arrangement of a heating element that canbe used to provide heat to the bellows assembly of FIG. 2A.

FIG. 5A illustrates an insulating enclosure that can be placed aroundthe bellows assembly of FIG. 2A.

FIG. 5B illustrates an additional implementation of an insulatingenclosure that can be placed around the bellows assembly of FIG. 2A.

FIG. 5C illustrates an additional implementation of an insulatingenclosure that can be placed around the bellows assembly of FIG. 2A.

FIG. 5D illustrates an additional arrangement to provide heated to gaswithin the bellows assembly of FIG. 2A.

FIG. 6A depicts structure that can be used to support the bellowsassembly of FIG. 2A.

FIG. 6B depicts a further example of supporting the bellows assembly ofFIG. 2A.

DETAILED DESCRIPTION

FIG. 1 depicts a two-phase immersion-cooling system 100 that can removeheat from semiconductor dies 180 during operation of the semiconductordies. The immersion-cooling system 100 includes a tank 110 containing acoolant liquid 150 that fills a first portion of the tank's enclosedvolume 112. Above the coolant liquid 150 is an air space 114 (alsoreferred to as a “head space”) filling a second portion of the tank'svolume 112. A condenser coil 132 can be located in the air space 114 tocondense coolant-liquid vapor 140 rising from the coolant liquid 150.The condenser coil 132 can carry a coolant that is circulated throughthe condenser coil 132 by a chiller 130.

A bellows assembly 120 can be fluidically coupled to the air space 114of the tank 110. Gas from the air space 114 can be received into abellows volume 122 enclosed by the bellows assembly 120 when pressure ofthe gas in the air space 114 increases. Additionally, gas can beexpelled from the volume 122 and returned to the air space 114 whenpressure of the gas in the air space 114 decreases. The tank 110 andbellows assembly 120 are coupled by at least one port 124 in a way toform a normally-closed system for gas within the air space 114 andbellows volume 122.

In some implementations, one or move isolation valves 125 can be locatedbetween the tank 110 and the bellows assembly 120, such that the bellowsvolume 122 can be valved off and isolated from the air space 114 in thetank. However, in some implementations, isolation valve(s) 125 may notbe included in the system. The valve(s) can be manual valves orautomated valves. The tank 110 can include an access door 111, which maybe located on a top or side of the tank. The access door 111 can be usedto install, swap, and/or remove circuit boards (PCBs) 160 within thetank 110. In some cases, the PCBs can be hot-swapped (exchanged whilethe system is in operation and other PCBs 160 are running and beingcooled). A PCB 160 to be exchanged can be shut down and removed throughthe access door 111. The access door 111 can slide open rather thanswing open to reduce turbulence in the air space 114 that would ejectvapor from the tank 110. Because the air space 114 and bellow volume 122can be under pressure when the system is operating, it can be beneficialto valve off the bellows volume 122 before opening the access door 111.Isolating the bellows volume 122 with the isolation valve(s) 125 canprevent pressure and/or the heavier coolant liquid vapor from enteringthe air space 114 when the access door is opened and forcing coolantliquid vapor out of the tank 110.

The closing and opening of isolation valve(s) 125 can be manual in someimplementations. In other implementations, a sensor 116 can be includedin the immersion-cooling system 100 to detect when the access the accessdoor 111 is being opened. For example, the sensor may detect motion oran unlocking of the access door 111. A signal from the sensor 116 can bereceived and processed by a controller 118, which can issue a commandsignal that causes the isolation valve(s) 125 to close. For example, theisolation valve(s) 125 can be driven by electromagnetic actuator(s) thatare activated in response to the command signal. The controller 118 canbe programmed to further issue a command signal to open the isolationvalve(s) 125 in response to receiving a signal from the sensor 116indicating that the access door 111 is closed.

The immersion-cooling system 100 can include one or morepressure-release valves 126 to release gas when a pressure in the airspace 114 and/or bellows volume 122 exceeds a predetermined threshold(referred to as an overpressure event). The bellows volume 122 acts as asecondary containment unit that assists in the normal operation of thetwo-phase immersion cooling system 100 and also accommodates asignificant portion if not all of the volume of air, air/vapor mixturein the tank's air space 114 with an intention to avoid or significantlyreduce the loss of coolant-liquid vapor 140 from the immersion-coolingsystem 100 during an overpressure event, as described in further detailbelow. The immersion-cooling system 100 may or may not further include abellows heater 190, depicted as a heating coil 192 in the illustrationof FIG. 1 .

There can be a plurality of semiconductor dies 180 mounted on one ormore printed circuit boards 160 that are immersed in the coolant liquid150. There can be one or more types of semiconductor dies, such as butnot limited to, a microprocessor (e.g., a central processing unit (CPU)and/or graphic processing unit (GPU)), a digital signal processing (DSP)die, an application-specific integrated circuit (ASIC),field-programmable gate array (FPGA), and/or other densely patternedsemiconductor die. One or more semiconductor dies 180 can be mounted inan electronic device package 170 that mounts to the PCB 160. The devicepackage 170 can include a heat-dissipative element thermally coupled tothe semiconductor dies 180 to dissipate heat from the semiconductor dies180 into the coolant liquid 150. Examples of such heat-dissipativeelements are described in U.S. provisional application Ser. No.63/489,895 filed on Mar. 13, 2023, titled “Electronic PackageConstruction for Immersion Cooling of Integrated Circuits,” whichapplication is incorporated herein by reference in its entirety. Theheat-dissipative element can thermally couple to the semiconductor die180 with or without a protective lid over the semiconductor die.

In the two-phase immersion-cooling system 100, heat flows from thesemiconductor dies 180, where the heat is generated during operation ofthe semiconductor dies, into the heat-dissipative element which is inphysical and thermal contact with the coolant liquid 150. The amount ofheat delivered to the coolant liquid 150 is enough to boil the coolantliquid. The heating and boiling of the coolant liquid 150 produces thecoolant-liquid vapor 140 that rises to the condenser coil 132. Thecoolant-liquid vapor 140 can be cooled and condensed back to liquiddroplets 142 by the condenser coil 132. The liquid droplets 142 from thecondensed vapor 140 can drip and/or flow back to the coolant liquid 150.

FIG. 2A illustrates an example of the bellows assembly 120 in furtherdetail. The bellows assembly 120 can be used with the two-phaseimmersion-cooling system of FIG. 1 . In some implementations, thebellows assembly 120 can be used with single-phase immersion-coolingsystems (e.g., when coolant liquids based on fluorochemistry are used asthe immersion coolant). A perspective view of the bellows assembly isillustrated with partial transparency to reveal features inside theassembly. The bellows assembly comprises a container 210 that can beformed, at least in part, from polymer (e.g., polyurethane, mylar,polyethylene, silicone, etc.) The container 210 has an interior surface215 spanning a surface area that encloses the volume 122 within thecontainer 210. The container can have a rectangular shape, as depicted,or may have another shape (e.g., square, disc, oval, polygonal). Atleast a portion of the container 210 is reversibly deformable toincrease and decrease an amount of the volume 122 enclosed by thecontainer 210 when pressure inside the container changes.

There can be one or more mounting hardware elements 220 attached to thecontainer 210 to securely mount the bellows assembly 120 in a desiredorientation (e.g., vertical as depicted, horizontal, or in any otherorientation). A vertical orientation is one in which a deformable wallof the container having a largest area among the container walls (e.g.,first wall 211 or second wall 212) is standing on edge, orientedperpendicular to the Earth's ground or floor on which theimmersion-cooling system rests. The mounting hardware elements 220 canbe located to reduce their interference with deforming walls of thecontainer 210. For example, the mounting hardware elements 220 can belocated at or near corners of the container 210 and/or at or near edgesof the container walls 211, 212, 213.

The illustration of FIG. 2A shows D-rings for the mounting hardwareelements 220 that are located at or near eight rounded corners of thecontainer 210. Although FIG. 2A depicts eight mounting hardware elements220 for the container 210, there can be from one to twenty mountinghardware elements 220 or even more arranged on the container 210 tosupport the bellows assembly 120. The mounting hardware elements 220 cancouple to external structure to stabilize the bellows assembly 120adjacent to the tank 110 (e.g., over or beside the tank). In someimplementations, described further below, there may be no mountinghardware elements 220 attached to or integrally formed with thecontainer 210.

The mounting hardware elements 220 can be metallic or formed from apolymer. In some implementations, each mounting hardware element 220 canbe attached to the container 210 (e.g., with a strap 224, tape, oradhesive). In some cases, each mounting hardware element 220 can attachto a feature on the container, such as a ridge or tab 226 that isintegrally formed on an exterior surface of a wall 211, 212, 213 oralong edges of the container 210. For example, an O-ring or D-ring 223can pass through a hole 225 in the ridge or tab 226 that is integrallyformed on an exterior surface of a wall 213, as depicted in FIG. 2B.

In some implementations, each mounting hardware element 220 can beintegrally formed on an exterior wall 213 of the container 210. Forexample, the mounting hardware element 220 can be an integrally formedridge or tab 226, as depicted in FIG. 2C, that includes a hole 227therethrough to allowing mounting of the container (via a screw, bolt,pin or other fastener) to an exterior structure. The hole 227 can beoriented vertically, as depicted in FIG. 2C, or horizontally, asdepicted by the hole 225 in FIG. 2B.

Inside the container 210 can be one or more venting conduits 240 (e.g.,tubes) that fluidically couple to the port(s) 124. The ventingconduit(s) can allow for ingress and egress of gas into and out of thebellows volume 122. The venting conduits 240 can include one or morevent holes 242 located to avoid being plugged by collapsing walls of thecontainer 210. For example, the vent holes 242 are arranged such thatgas exiting the vent holes 242 into the bellows volume 122 flows in adirection that is approximately parallel to (within 20 degrees), or notnormal to, at least one deformable wall, such as the first wall 211(occluded in the drawing) and second wall 212 of the container 210.

For the implementation of FIG. 2A, each port 124 comprises a doubleflange assembly, which can reduce gas flow impedance and/or provideadditional support for the container 210 and/or venting conduits 240within the container. However, a single flange assembly can be used insome cases, an example of which is described further below in connectionwith FIG. 3A.

The container 210 can include at least the first wall 211, second wall212, and third wall 213 that enclose at least a portion of the bellowsvolume 122, as depicted in FIG. 2D. In an ambient environment, whenthere is no pressure differential across the walls of the container 210,the first wall 211 and second wall 212 can be approximately parallel toeach other (i.e., within 20 degrees of being parallel to each other,including being exactly parallel). The first wall 211 can span a firstsurface area and the second wall 212 can span a second surface area,which may be a same amount as or different amount than the first surfacearea. The first surface area and the second surface area can form amajority of the interior surface 215 of the container 210 that enclosesthe volume 122. The first wall 211 can be separated from the second wall212 by a space occupied by at least a portion of the volume 122. Theseparation distance d between the first wall 211 and second wall 212 canbe from 5 millimeters (mm) to 500 mm, though smaller or larger distancescan be used. In some cases, the separation distance d can be from 100 mmto 500 mm. The third wall 213 can connect to the first wall 211 andconnect to the second wall 212 and can extend part way or all the wayaround a periphery of the container 210. In FIG. 2A the third wall 213extends all the way around the container 210. In other implementations,the container can have six distinct walls (e.g., front, back, top,bottom, left side, right side).

At least one of the first wall 211, second wall 212, and third wall 213comprises (or comprise) a flexible polymer that allows the wall(s) todeform when the pressure of gas within the volume 122 changes. Thethickness of the flexible polymer can be from 0.1 mm to 3 mm, thoughthinner or thicker polymer may be used in some cases. In some cases, thethickness of the flexible polymer can be from 0.5 mm to 2.5 mm. Thefirst wall 211 and second wall 212 can have a same rectangular shape, asdepicted in FIG. 2A, or may have another shape (e.g., square, disc,oval, polygonal). The first wall 211 and second wall 212 each can spanan area (in x and y directions in FIG. 2A) from 0.2 square meter (m²) to3 m², though larger walls may be used for the container 210. In somecases, the first wall 211 and second wall 212 each can span an area from0.5 m² to 3 m². The volume 122 within the container 210 can occupy from0.05 cubic meter (m³) to 3 m³, though larger volumes may be used in somecases. In some implementations, the volume 122 can occupy from 0.5 m³ to2 m³.

FIG. 2E and FIG. 2F depict an implementation where the first wall 211and the second wall 212 comprise a flexible polymer, whereas the thirdwall 213 is comparatively stiffer. For example, the third wall 213 canbe thicker and/or formed from a different material than the thickness ofand/or material used to form the first wall 211 and the second wall 212.Under positive pressure (depicted in FIG. 2E), gas within the volume 122pushes the first wall 211 and second wall 212 outward, away from thecenter of the container 210 (marked by the x symbol in the drawing).This increases the bellows volume 122 to accommodate more gas from thetank 110. Under negative pressure or vacuum (depicted in FIG. 2F),ambient air outside the volume 122 pushes the first wall 211 and secondwall 212 inward, toward the center of the container 210. This decreasesthe bellows volume 122, returning gas to the tank 110.

Although FIG. 2E and FIG. 2F depict an implementation where two wallscomprise flexible polymer and can deform, in another implementation onlyone wall (e.g., the first wall 211) can comprise a flexible polymer anddeform according to changes in pressure of the gas within the bellowsvolume 122. In such implementations, at least one of the walls 211, 212,213 can differ from at least one other wall of the container 210. Forexample, one or more walls 211, 212, 213 may differ in materialcomposition and/or thickness such that one wall is comparatively stiff,and flexes insignificantly compared to another wall of the container210. When the container 210 includes a stiff wall or walls, the ports124, pressure-release valve 126, and/or mounting hardware elements 220can be attached to the stiff wall or walls. Further, a heating elementand/or insulating enclosure (described in more detail below) can beattached to and/or supported by the stiff wall or walls. In anotherimplementation, the first wall 211, second wall 212, and third wall 213can all comprises a flexible polymer and deform according to changes inpressure of the gas within the bellows volume 122.

According to some implementations, the bellows assembly 120 is mountedwith the mounting hardware elements 220 such that the container 210 isin a vertical orientation, as depicted in FIG. 1 and FIG. 2A. In avertical orientation, the wall(s) 211, 212 of the container 210 thatundergo the most deformation due to changes in pressure of gas withinthe bellows volume 122 can move horizontally and without hindrance byany external structure. The horizontal direction would be parallel to afloor on which the immersion-cooling system 100 rests. In such anorientation, two or more bellows assemblies 120 could be mountedend-to-end, side-by-side (with appropriate spacing therebetween), and/orabove and below each other to service one tank 110.

Other mounting orientations are possible, including horizontal. Thecontainer 210 may be mounted horizontally using the same or differentmounting hardware elements. In a horizontal orientation, the wall(s)211, 212 of the container 210 that undergo the most deformation due tochanges in pressure of gas within the bellows volume 122 can movevertically and without hindrance by any external structure. In ahorizontal orientation, two or more bellows assemblies 120 could bemounted above and below each other to service one tank 110.

Referring again to FIG. 1 , changes in pressure of gas within thebellows volume 122 can be caused by changes in operation of thesemiconductor dies 180 within the tank 110 of the immersion-coolingsystem 100. For example, when all semiconductor dies 180 in the tank 110are operating at full capacity, they will generate a significant amountof heat that causes the most amount of boiling of the coolant liquid150. This boiling at peak operation produces the most amount ofcoolant-liquid vapor 140 from the coolant liquid 150 that goes into theair space 114, heating air in the air space and increasing pressure inthe air space. The increased pressure of the gas within the air space114 forces gas from the air space 114 into the bellows volume 122 via atleast one port 124 and expands the container 210, as depicted in FIG.2E. If an over-pressure event occurs during peak operation, gas can bevented from the system (as described further below). When operation ofthe semiconductor dies 180 decreases such that only one or a fewsemiconductor dies are operating at low capacity, the coolant liquid 150can cool and the amount of coolant-liquid vapor 140 in the air space 114can decrease, creating a comparative vacuum or negative pressurecondition in the air space 114 with respect to the bellows volume 122.This negative pressure condition in the air space 114 allows thecontainer 210 to expel gas from the bellows volume 122, through theport(s) 124, and back into the air space 114. In some cases, thenegative pressure in the air space can pull gas from the bellows volume122, causing the container to deform inward as depicted in FIG. 2F.

When gas pressure within the air space 114 and/or bellows volume 122exceeds a predetermined pressure threshold, it can be vented through apressure-release valve 126. High pressure within the air space 114 canbe undesirable because it can change the boiling temperature of thecoolant liquid 150. Accordingly, the pressure threshold for release ofgas may be a small amount above the ambient pressure (e.g., from 0.2 psito 3 psi above the ambient pressure around the immersion-cooling system100), though a higher pressure-release threshold can be used in someimplementations. When pressure exceeds the pressure threshold value, thepressure-release valve 126 can open to release gas from the system.According to some implementations, the container 210 is configured tocontrollably rupture (rather than explode) at a second pressurethreshold that is higher than the pressure-release threshold. Forexample, a seam or groove formed in the container 210 can be configuredto tear at a second pressure threshold that is from 2 psi to 10 psihigher than the pressure release threshold. The controlled rupture canoccur if a pressure-release valve sticks, for example.

The inventors have recognized and appreciated that some coolant liquids150 are expensive and that venting coolant-liquid vapor 140 into anambient environment can incur a significant operating expense for theimmersion-cooling system 100. Accordingly, the pressure-release valve126 can be located in the system 100 to reduce an amount ofcoolant-liquid vapor 140 released during an over-pressure event. Sincethe coolant-liquid vapor 140 can be heavier than air and heavier thanwater vapor, the pressure-release valve 126 can be located at a highelevation in the immersion-cooling system 100. At a higher elevation,the partial pressure and content of coolant-liquid vapor 140 can belower than the partial pressure and content of the coolant-liquid vapor140 at a lower elevation, near the coolant liquid 150, in the system.For example, the coolant-liquid vapor 140 can be comparatively denserthan air so that the air molecules (oxygen, nitrogen) in the tank 110are relatively lighter. The difference in densities between air andcoolant-liquid vapor 140 will cause the air molecules to rise upwardsand the coolant-liquid vapor 140 to stay relatively lower. Therefore,when the air is pushed upwards by the coolant-liquid vapor 140 from thecoolant liquid 150 in the tank 110, air will move up from the air space114 in the tank 110 to the container 210. Instead of mounting apressure-release valve 126 directly to the tank 110, thepressure-release valve 126 can be located above the tank 110 (e.g., onan extension pipe the extends vertically above the tank and/or bellowsassembly 120, or high on the container 210 of the bellows assembly 120).

For implementations like that depicted in FIG. 1 , the bellows assembly120 is located vertically above the tank 110 and the pressure-releasevalve(s) 126 can be located at or near a top edge of the container 210.For example, the pressure-release valve(s) 126 can be located within 10centimeters (cm) of an edge 219 of a wall of the container 210, or evenwithing 5 cm of an edge 219 of a wall of the container 210, where theedge is a top edge of the container 210 when the bellows assembly 120 ismounted to service the tank 110 during operation of theimmersion-cooling system 100. In some implementations, thepressure-release valve(s) 126 can be located on a top, upward facingwall of the container 210. When a pressure-release valve 126 mountedhigh in the system opens during an over-pressure event, it can ventproportionately more air and/or water vapor and less coolant-liquidvapor 140 from the system than the valve would vent if located at alower elevation in the system (e.g., in the tank 110 closer to thecoolant liquid 150 or near the bottom of the bellows assembly 120).

The bellows assembly 120 can include one or more ports 124 to admit gasinto the bellows volume 122 from the air space 114 in the tank 110 andto expel gas from the bellows volume 122 back to the air space 114. Theport(s) can include hardware elements that attach to the container 210of the bellows assembly 120. A port 124 may also be used to attach eachpressure-release valve 126 and or a sensor to the container 210.

FIG. 3A depicts, in cross-section and partial exploded view, one exampleof a port 124 that can attach to the container 210. The port 124 caninclude a port insert 310 that includes a flange 312 having a pluralityof flange holes 314 through the flange 312. The flange holes 314 can bedistributed around the flange 312. The port insert 310 can include atleast one exterior conduit 315 that fluidically couples to at least oneinterior conduit 317. The interior conduit 317 can be arranged to passthrough the container wall 213 and extend into the interior of thecontainer 210 when the port insert 310 is mounted to a wall (e.g., thethird wall 213) of the container 210. In some cases, the interiorconduit 317 fluidically couples to the venting conduit 240 or isconfigured to be the venting conduit 240 (e.g., by having at least onehole to vent gas as described above for the venting conduit 240 of FIG.2A. In some implementations, the flange 312 can be welded or otherwiseadhered to a conduit to make the port insert 310. One or both of theinterior conduit 317 and exterior conduit 315 can have a smooth outersurface (as shown) or may have a barbed outer surface for attaching aflexible hose or a tube.

A region of the container wall 213 where the port 124 mounts can includean entry hole 302 to receive the port insert 310 and may or may notinclude a ring 306 of increased wall thickness surrounding the entryhole 302. There can be a plurality of container screw holes 304 in thecontainer wall 213 surrounding the entry hole 302 and having a patternthat matches the pattern of the plurality of flange holes 314 in theflange 312. Threaded rivet inserts 330 can be placed in the holes 304through the container wall 213 and tightened to engage the rivetingaction and provide threaded nuts secured to the container 210.

To seal the port insert 310, exterior conduit 315, and interior conduit317 to the container 210, a gasket 320 can be located between the flange312 and the container wall 213. In some cases, the gasket 320 can beformed from a soft material (e.g., silicone or a closed-cell foam).Additionally or alternatively, the gasket 320 can be formed in place(e.g., by applying silicone or another sealant on the flange 312 and/orcontainer wall 213 where the flange 312 mates to the wall 213). Thegasket 320 can include a plurality of holes 322 that align with screwholes 304 in the container and with the plurality of flange holes 314.Machine screws (not shown) can then be inserted through the flange holes314, through the gasket 320, and into the threaded rivet inserts 330.The machine screws can be tightened to seal the port insert 310 to thecontainer. Flexible washers 340 may or may not be used to as anadditional seal around each flange hole 314 (e.g., to prevent gas fromescaping through the threads of the machine screws).

Once sealed to the container 210, a conduit (e.g., a tube or hose) canbe attached to the exterior conduit 315 of the port insert 310. Theconduit can also connect at a distal end to a port 124 on the tank 110to fluidically couple the volume 122 of the container 210 to the airspace 114 in the tank 110. In some cases, a flexible hose can slide overthe exterior conduit 315 and be secured with a hose clamp. In somecases, the exterior conduit 315 can include hose barbs and a flexiblehose can be pushed over the barbs to secure the hose. In someimplementations, a tube having an inner diameter large enough to slideover the exterior conduit 315 (or outer diameter small enough to fitinside the exterior conduit 315) can be adhered to the exterior conduit315 with an adhesive and/or crimped onto the exterior conduit.

FIG. 3B depicts another implementation of a port insert 311 that may beused alternatively in the port assembly of FIG. 3A. In thisimplementation, the port insert 311 includes a first flange 312 and asecond flange 313. Both flanges can include a plurality of flange holes,which may be arranged in the same or different patterns around theexterior conduit 315. The first flange 312 can be used to attach theport insert 310 to the container 210 of a bellows assembly 120. Thesecond flange 313 can attach with machine screws and a gasket to amating flange on the tank 110 of the immersion-cooling system 100, forexample.

Because the port inserts 310, 311 can be made from a rigid material(e.g., a metal or stiff polymer), they can provide mechanical support tothe container 210 of the bellows assembly 120. For example, one or moreport inserts 310, 311 can rigidly couple to the tank 110 via the secondflange 313 and/or exterior conduit 315 and provide adequate support forthe container 210 and bellows assembly 120, as depicted in FIG. 6B. Insuch implementations, mounting hardware elements 220 may not be includedon the container 210.

FIG. 3C depicts another implementation of a port 124. In thisimplementation, an exterior port insert 311 a and an interior portinsert 311 b are located outside and inside the container 210,respectively. The exterior port insert 311 a comprises an exteriorconduit 315 connected to a first flange 312. The interior port insert311 b comprises an interior conduit 317 connected to a second flange316. Each flange can connect to its conduit by welding or an adhesive.The first flange 312 can include a first plurality of holes 314 and thesecond flange 316 can include a second plurality of holes 327 that alignto each other. Threaded blind inserts 331 can be placed in the secondplurality of holes 327, or the holes 327 themselves can be threaded andthe blind inserts not used. Two gaskets 320, 321 with aligned holes 322,323 can be placed on either side of the container wall 213 to seal theport inserts 311 a, 311 b to the container wall 213. To get the interiorport insert 311 b inside the container, the entry hole 302 in thecontainer wall 213 and the flanges 316, 312 can be oval or oblong.Machine screws or bolts can be placed through the holes to engagethreads in the blind inserts 331 to clamp the assembly together.

FIG. 3D depicts another implementation of an exterior port insert 311 athat can be used in the port assembly of FIG. 3C. The exterior portinsert 311 a includes a second flange 313 to provide for coupling toanother flange or device. For example, the second flange 313 couldcouple to a flange on the tank 110 of the immersion-cooling system 100.

FIG. 3E is an illustration of one example of a port 124 that could beused with the container 210. The port 124 includes an additionalexterior conduit 315 a that is connected to the flange 312. In someimplementations, the second flange 313 a of the exterior conduit(s) maynot contain holes and may be quick-release type flanges, for example.

The port 124 can also be used to fluidically couple the pressure-releasevalve 126 to the container 210 of the bellows assembly 120. For example,the pressure-release valve 126 can couple to or directly mount onto theexterior conduit 315 of the port insert 310 of FIG. 3A, or thepressure-release valve 126 can couple to or directly mount onto thesecond flange 313 of the port insert in FIG. 3B or FIG. 3D. Thepressure-release valve 126 can also couple to the exterior port insert311 a of FIG. 3C.

In some implementations, at least one vapor barrier can be used in theimmersion-cooling system 100 to block the flow of the coolant-liquidvapor 140 and/or water vapor from reaching some parts of the system.FIG. 3A depicts one implementation of a vapor barrier 350 that can bemounted in a port insert 310 of a port 124. The vapor barrier 350 cancomprise a membrane with micrometer-scale or nanometer-scale holes thatare sized to block the flow of coolant-liquid vapor 140 and/or watervapor past the vapor barrier 350, and yet allow the flow of airmolecules (e.g., oxygen and nitrogen gases) to pass through the vaporbarrier. In some implementations, the vapor barrier can comprise anactivated filter to capture coolant-liquid vapor 140 and/or water vapor.

One or more different or same vapor barriers 350, or a mixture of sameand different vapor barriers, can be used in the immersion-coolingsystem 100. For example a first vapor barrier 350 can be used to blockthe flow of coolant-liquid vapor 140 into the bellows volume 122 and/orto block the flow of coolant-liquid vapor 140 into a pressure-releasevalve 126. A second vapor barrier may be located to capture water vaporpassing between the air space 114 and the bellows volume 122. The vaporbarrier(s) 350 (which can comprise a molecular sieve, desiccant,adsorbent, or some combination thereof) can be located in one or moreplaces within the immersion-cooling system 100 (e.g., at ports 124 onthe tank 110, at ports 124 of the bellows assembly 120 including thoseused to mount one or more pressure-release valves 126, and within thecontainer 210 (e.g., partitioning the bellows volume 122 into tworegions where one region contains the pressure-release valve(s) 126. Thevapor barrier(s) 350 can be located to block coolant-liquid vapor 140from entering the region contains the pressure-release valve(s) 126.

The inventors have further recognized and appreciated that condensing ofcoolant-liquid vapor 140 and water vapor in the bellows assembly 120 canbe undesirable. For example, the coolant liquid 150 may contain afluoroketone that can react with liquid water and create an acid. Theacid may be corrosive to some components in the system. By blocking theflow of water vapor that would otherwise flow back into the tank 110from the bellows volume 122 and/or capturing water vapor (e.g., with adesiccant in the vapor barrier 350), the creation of acid in the tankcan be prevented.

Condensation of water vapor and/or coolant-liquid vapor 140 in thebellows assembly 120 can be prevented by heating the bellows assemblyand/or providing heat to the gas within the container 210. One approachto providing heat to the gas within the container 210 is depicted inFIG. 1 . A heater 190 comprising a heating coil 192 can carry aheat-transfer liquid (e.g., water or a mixture comprising ethyleneglycol) to heat gas within the bellows volume 122. The heating coil 192can be inside the container 210 of the bellows assembly 120 (e.g.,directly heating gas within the bellows volume 122) or can be externalto the container 210 (e.g., heating walls of the container 210). Theheating coil 192 can be part of a closed-loop fluid circuit 195 thatextends into the coolant liquid 150 within the tank 110 where heat iscoupled to the heat-transfer liquid by a coil 197 immersed in thecoolant liquid 150. There can be one or more fluid circuits 195providing heat to one or more bellows assemblies 120 in animmersion-cooling system 100. Ports 124 like those described above inconnection with FIG. 3A and FIG. 3B can be used to pass the fluidconduit of the heating circuit 195 through walls of the container 210and through walls of the tank 110. The heater 190 can be passive in somecases (e.g., relying on thermally-induced flow of the heat-transferliquid in the system) or can be active (e.g., mechanical pumping of theheat-transfer liquid and/or heated by an external active heat sourceinstead of entering the tank 110 and being heated by the coolant liquid150). In some cases, the heat-transfer liquid can be a phase changematerial (PCM) that changes into a vapor phase when heated in the tank110 by the coolant liquid 150 or when heated by an external source.

Other types of heaters 190 can be used for the bellows assembly 120.FIG. 4A depicts an implementation where an electrically-resistiveheating element 410 is thermally coupled to a wall 212 of the container210. The heating element 410 can be a flexible heating pad, resistivewire, silicone heater, a heating element embedded in rubber orfiberglass, an etched foil flexible heater, polyimide heater, heatingtape, Peltier, or thermoelectric heater. In some cases, the heatingelement 410 (such as a silicone heater) can form at least a portion of awall of the container 210.

FIG. 4B depicts another heating arrangement where theelectrically-resistive heating element 410 enters into the bellowsvolume 122 to heat gas directly inside the container 210. The heatingelement 410 may connect to a port insert 310 of a port 124 describedabove in connection with FIG. 3A and FIG. 3B.

Another method of providing heat to the bellows assembly 120 can besimilar to that shown in FIG. 1 except that the heat for the fluidcircuit 195 is provided by another source instead of the coolant liquid150. In one example, the fluid circuit 195 can be an extension of thefluid circuit 135 connected to the chiller 130. The return line from thecondenser coil 132 can be extended to run to a heating coil 192 in thebellows assembly 120 before returning to the chiller 130, as depicted bythe fluidic circuit extension 137 in FIG. 1 (dashed, shaded lines). Heatreceived from condensing coolant-liquid vapor 140 in the tank 110 can beprovided to the bellows assembly 120. In another example, the fluidcircuit 195 can run to the chiller 130 instead of the tank 110 andreceive heat from the chiller 130 that is generated in the process ofcooling liquid coolant circulated through the condenser coil 132.

In some implementations, a heater 190 can provide heat to an enclosuresurrounding the bellows assembly 120, such as the insulated enclosure510 depicted in FIG. 5A. The inventors have recognized and appreciatedthat some operating environments, such as those at data centers, can becool and may cause condensing of water vapor and/or coolant-liquid vapor140 in the bellows assembly 120. Accordingly, an insulated enclosure 510can be placed around the bellows assembly, as illustrated in FIG. 5A.The insulated enclosure 510 can comprise an insulation 512 that linesmost of the enclosure 510. The insulation 512 can comprise a foam, afiberglass insulation, and/or a heat reflecting barrier that is arrangedto reflect heat back inside the insulated enclosure 510. Insulating foamcan be flexible (e.g., Armaflex® foam sheet insulation) or can comprisean expanded polystyrene such as Styrofoam®. In some cases, the enclosure510 can further include a shell 520 surrounding the insulation 512. Theshell 520 can form an outer protective surface and can be made from adifferent material than the insulation 512 (e.g., a metal, polymer, orcomposite material such as fiberglass). In some implementations, theinsulation 512 can be external to the shell 520. When an insulatedenclosure 510 is used, the heating element 410 can be mounted to thebellows assembly 120 (as depicted in FIG. 5A), between the bellowsassembly 120 and the insulated enclosure 510, or can be mounted to theinsulated enclosure 510 (as depicted in FIG. 5B). In someimplementations, the insulated enclosure 510 is sized to avoidinterfering with motion of the deformable wall(s) 211, 212, 213 of thecontainer 210 when the container expands and contracts.

The insulated enclosure 510 can be mounted on top of the tank 110, insome implementations. In such cases, heat from the tank that is capturedby the insulated enclosure 510 may be sufficient to heat the bellowsassembly 120 and prevent condensing of water vapor and/or coolant-liquidvapor 140 in the container 210. In such cases, a heater 190 and heatingelement 410 may not be included.

In some implementations, the container 210 can be insulated with aflexible insulation layer applied to at least some of the walls of thecontainer. FIG. 5C depicts such an implementation where flexibleinsulation 512 is applied to at least portions of at least three wallsof the container 210. In some cases, the insulated enclosure 510comprises an insulative blanket that fits over the bellows assembly 120.In an additional example, the flexible insulation 512 can be a sheet ofinsulation that is adhered to one or more walls of the container 210. Ina further implementation, the insulation 512 can be sprayed onto andadhered to the walls of the container 210. In yet an additional example,the insulated enclosure 510 can be constructed to behave like a bellowsand may or may not use an inflatable container 210 inside the enclosure510. In such an example, the insulated enclosure 510 can have ports 124and the pressure-release valve(s) 126 mounted directly on the enclosure510.

Another approach to heating the gas within the bellows volume 122 is tothermally couple at least a portion of one wall of the container 210 toa wall of the tank 110, as depicted in FIG. 5D. The wall 212 of thecontainer 210 that thermally couples to the wall of the tank 110 maycomprise a metal or other thermally conductive material. In some cases,a thermally-conductive adhesive or paste can be used to improve heattransfer from the tank 110 to the container 210. An insulation 512 cansurround at least a portion of the container 210. One or more ports 124can couple the air space 114 in the tank 110 to the bellows volume 122.The port(s) 124 can be located on a side of the container 210 (asillustrated in the arrangement on the left side of FIG. 5D) or can belocated on a bottom wall 213 of the container and connect to anotherport through the side wall of the tank 110 (as illustrated in thearrangement on the right side of FIG. 5D). One or more isolation valves125 can be used in the arrangement of FIG. 5D (e.g., included within aport 124 or located between a port 124 on the bottom wall 213 of thecontainer 210 and the side wall of the tank 110).

According to some implementations, one or more walls 211, 212, 213 ofthe container 210 can be made from an insulative material, such as aclosed-cell, flexible foam insulation that is impervious to gas flow.The ports 124 and the pressure-release valve(s) 126 can be mounteddirectly on the insulative walls of the container 210. There may or maynot be additional insulation around the container 210.

FIG. 6A depicts an example of support structure 600 that can be used tosuspend or support one or more bellows assemblies 120 above a tank 110.Such a support structure can be used, for example, when flexible tubingis used to fluidically couple the container 210 to the tank 110 viaports 124. The support structure 600 comprises vertical risers 610 thatinclude mounting hardware elements 620 (e.g., tabs, pins, holes, etc.)to couple to mounting hardware elements 220 on the container 210. Insome implementations, horizontal struts having mounting hardwareelements 620 could be used instead of the vertical risers 610 to engagewith mounting hardware elements 220 on the container. There can be asfew as one vertical riser 610 (or horizontal strut) at opposing ends orsides of the bellows assembly 120 to support the bellows assembly,though more vertical risers 610 and/or horizontal struts can be used.The support structure 600 may or may not be part of a framework that canbe suspended from above (e.g., attached to overhead rails or otherstructure) or supported from below (e.g., mounted to the top of the tank110 and/or to the floor on which the immersion-cooling system rests). Insome cases, the support structure 600 can be supported from lateralstructure (e.g., by walls or posts rising adjacent to the tank 110).

FIG. 6B depicts an example where the bellows assembly 120 is supportedby one or more stiff conduits 630 (e.g., stiff tubes) that fluidicallycouple the bellows assembly to the tank 110. The conduit(s) 630 canconnect to ports 124 on the bellows assembly 120 and tank 110. In suchcases, no other support structure may be needed to support the bellowsassembly. The stiff conduits 630 can comprise a metal and/or polymer andbe of sufficient strength to support the bellows assembly 120 withoutcollapsing.

Bellows for immersion cooling can be implemented in differentconfigurations and operated according to different methods, some ofwhich are listed below.

(1) A bellows assembly for a two-phase immersion cooling system, thebellows assembly comprising: a container comprising a polymer andenclosing a volume, the container having a first surface spanning afirst surface area that encloses the volume, wherein at least a portionof the container is reversibly deformable to increase and decrease anamount of the volume enclosed by the container; a first wall comprisingthe polymer and having a second surface spanning a second surface area;a second wall having a third surface spanning a third surface area, thesecond wall separated from the first wall by at least a portion of thevolume and oriented approximately parallel to the first wall when thevolume is not under pressure or vacuum, wherein the second surface areaand the third surface area comprise a majority of the first surfacearea; a third wall extending between and connected to the first wall andthe second wall; at least one port in the third wall to admit gas intothe volume and expel the gas from the volume; and at least one hardwareelement attached to at least one of the first wall, the second wall, andthe third wall to mount the container in an orientation such that atleast one of the first wall and the second wall deforms or deformoutward from a center of the container without external hinderance whenthe volume is under pressure and deforms or deform inward withoutexternal hinderance when the volume is under vacuum.(2) The bellows assembly of configuration (1), wherein the second walland the third wall also comprise the polymer.(3) The bellows assembly of configuration (1) or (2), wherein a port ofthe at least one port includes a port insert comprising: a flange thatattaches to the third wall; a gasket; and a conduit passing through thethird wall and sealed to the third wall with the flange and the gasket.(4) The bellows assembly of configuration (3), wherein the conduitincludes one or more holes along a length of the conduit located insidethe container and the one or more holes are oriented such that gas flowsinto the container in a direction that is not normal to the firstsurface of the first wall and not normal to the second surface of thesecond wall.(5) The bellows assembly of any one of configurations (1) through (4),wherein the at least one hardware element comprises a D-ring attached toan external surface of the container.(6) The bellows assembly of any one of configurations (1) through (5),further comprising at least one pressure-release valve located within 10cm from an edge of the first wall and fluidically coupled to the volumesuch that the gas can be released from the volume when pressure withinthe volume exceeds a threshold value.(7) The bellows assembly of configuration (6), wherein apressure-release valve of the at least one pressure-release valve islocated within 10 cm of a top edge of the container such that, when thebellows assembly is in use in the two-phase immersion cooling system,the gas released from the volume contains a lower percentage ofcoolant-liquid vapor from coolant liquid used when the two-phaseimmersion cooling system is in operation than if the pressure-releasevalve of the at least one pressure-release valve were located at a lowerelevation on the first wall.(8) The bellows assembly of any one of configurations (1) through (7),further comprising: at least one pressure-release valve fluidicallycoupled to the volume such that the gas can be released from the volumewhen pressure within the volume exceeds a threshold value; and a vaporbarrier arranged to transmit air to the pressure-release valve and toblock passage of coolant-liquid vapor from coolant liquid used when thetwo-phase immersion cooling system is in operation.(9) The bellows assembly of any one of configurations (1) through (8),wherein the first wall and second wall deform away from and toward eachother in directions that are approximately horizontal, when the bellowsassembly is in use in the two-phase immersion cooling system.(10) The bellows assembly of any one of configurations (1) through (8),wherein the first wall and second wall deform away from and toward eachother in directions that are approximately vertical, when the bellowsassembly is in use in the two-phase immersion cooling system.(11) The bellows assembly of any one of configurations (1) through (10)in a combination with a heater arranged to provide heat to the gaswithin the volume such that coolant-liquid vapor contained within thevolume does not condense when the bellows assembly is in use in thetwo-phase immersion cooling system.(12) The bellows assembly of configuration (11), wherein the heatercomprises an electrical heating element thermally coupled to the bellowsassembly.(13) The bellows assembly of configuration (11), wherein the heatercomprises a conduit to carry a heated liquid into and out of thecontainer.(14) The bellows assembly of any one of configurations (1) through (13),further including insulation arranged to thermally insulate at least aportion of the container from an external environment.(15) The bellows assembly of any one of configurations (1) through (14),wherein at least one of the first wall, the second wall, and the thirdwall comprises thermal insulation.(16) The bellows assembly of any one of configurations (1) through (15),including a vapor barrier fluidically coupled to the volume to captureat least one gaseous component within the gas.(17) The bellows assembly of configuration (16), wherein the vaporbarrier is an adsorbing filter or desiccant arranged to capture one orboth of coolant-liquid vapor and water vapor from the gas admitted intothe volume.(18) The bellows assembly of configuration (16), wherein the vaporbarrier is an activated filter to capture coolant-liquid vapor fromcoolant liquid used when the two-phase immersion cooling system is inoperation.(19) The bellows assembly of any one of configurations (1) through (18),wherein a thickness of the first wall between 100 microns and 3millimeters.(20) The bellows assembly of any one of configurations (1) through (19),wherein the polymer comprises polyurethane.(21) The bellows assembly of any one of configurations (1) through (20),wherein the first wall and the second wall have a same rectangularshape.(22) The bellows assembly of any one of configurations (1) through (21),wherein an area of the first surface is greater than 0.2 m².(23) A method of regulating pressure in a two-phase immersion coolingsystem, the method comprising: receiving gas through a port and into avolume enclosed by a container of a bellows assembly in response to anincrease in pressure of the gas, the container having a first surfacespanning a first surface area that encloses the volume; deforming afirst wall of the container in a first direction to increase the volumewhile receiving the gas, wherein the first wall comprises a polymer andhas a second surface spanning a second surface area; expelling the gasfrom the volume in response to a decrease in pressure of the gas; anddeforming the first wall of the container in a second direction oppositethe first direction to decrease the volume while expelling the gas,wherein: the container includes a second wall having a third surfacespanning a third surface area, the second wall being separated from thefirst wall by at least a portion of the volume and orientedapproximately parallel to the first wall when the volume is not underpressure or vacuum, the second surface area and the third surface areacomprise a majority of the first surface area, the container furtherincludes a third wall extending between and connected to the first walland the second wall, and the bellows assembly includes at least onehardware element attached to at least one of the first wall, the secondwall, and the third wall to mount the container in an orientation suchthat at least one of the first wall and the second wall deforms ordeform outward from a center of the container without externalhinderance when the volume is under pressure and deforms or deforminward without external hinderance when the volume is under vacuum.(24) The method of (23), wherein the second wall and the third wall alsocomprise the polymer.(25) The method of (23) or (24), further comprising: directing the gasreceived into the volume such that the gas flows into the container in adirection that is not normal to the first surface of the first wall andnot normal to the second surface of the second wall.(26) The method of any one of (23) through (25), further comprising:releasing, with a pressure-release valve, gas from the volume into anambient atmosphere outside the container when pressure of the gas in thevolume exceeds a threshold value, wherein the pressure-release valve islocated is located within 10 cm of a top edge of the container such thatthe gas released from the volume contains a lower percentage ofcoolant-liquid vapor from coolant liquid used in the two-phase immersioncooling system than if the pressure-release valve were located at alower elevation on the container.(27) The method of (26), further comprising: blocking passage of thecoolant-liquid vapor to the pressure-release valve with a vapor barrier;and transmitting air molecules through the vapor barrier to thepressure-release valve.(28) The method of any one of (23) through (27), wherein the first walland second wall deform away from each other and toward each other indirections that are approximately horizontal when receiving the gas intothe volume and when expelling the gas from the volume, respectively.(29) The method of any one of (23) through (27), wherein the first walland second wall deform away from each other and toward each other indirections that are approximately vertical when receiving the gas intothe volume and when expelling the gas from the volume, respectively.(30) The method of any one of (23) through (29), further comprising:providing heat to the gas within the volume such that coolant-liquidvapor contained within the volume does not condense when the bellowsassembly is in use in the two-phase immersion cooling system.(31) The method of any one of (23) through (30), further comprisingproviding the heat with an electrical heating element thermally coupledto the bellows assembly.(32) The method of any one of (23) through (31), further comprisingproviding the heat with a conduit carrying a heated liquid into and outof the container.(33) The method of any one of (23) through (32), further comprisingretaining heat in the container with insulation arranged to thermallyinsulate at least a portion of the container from an externalenvironment.(34) The method of any one of (23) through (33), further comprisingcapturing, with a vapor barrier fluidically coupled to the volume, atleast one gaseous component within the gas.(35) A two-phase immersion cooling system comprising: a tank to containone or more printed circuit boards having one or more semiconductor diesto be cooled during operation of the semiconductor die(s); coolantliquid within the tank that immerses the one or more printed circuitboards; air space within the tank above the coolant liquid; and abellows assembly fluidically coupled to the air space and forming anormally-closed first volume that includes the air space, the bellowsassembly comprising: a container comprising a polymer and enclosing asecond volume that is a portion of the first volume, the containerhaving a first surface spanning a first surface area that encloses thesecond volume, wherein at least a portion of the container is reversiblydeformable to increase and decrease an amount of the second volumeenclosed by the container; a first wall comprising the polymer andhaving a second surface spanning a second surface area; a second wallhaving a third surface spanning a third surface area, the second wallseparated from the first wall by at least a portion of the second volumeand oriented approximately parallel to the first wall when the firstvolume is not under pressure or vacuum, wherein the second surface areaand the third surface area comprise a majority of the first surfacearea; a third wall extending between and connected to the first wall andthe second wall; at least one port in the third wall to admit gas intothe second volume from the air space when the first volume is underpressure and expel the gas from the second volume into the air spacewhen the first volume is under vacuum; and at least one hardware elementattached to at least one of the first wall, the second wall, and thethird wall to mount the container in an orientation such that at leastone of the first wall and the second wall deforms or deform outward froma center of the container without external hinderance when the firstvolume is under pressure and deforms or deform inward without externalhinderance when the first volume is under vacuum.(36) The two-phase immersion cooling system of configuration (35),wherein the second wall and the third wall also comprise the polymer.(37) The two-phase immersion cooling system of configuration (35) or(36), wherein a port of the at least one port includes a port insertcomprising: a flange that attaches to the third wall; a gasket; and aconduit passing through the third wall and sealed to the third wall withthe flange and the gasket.(38) The two-phase immersion cooling system of configuration (37),wherein the conduit includes one or more holes along a length of theconduit located inside the container and the one or more holes areoriented such that gas flows into the container in a direction that isnot normal to the first surface of the first wall and not normal to thesecond surface of the second wall.(39) The two-phase immersion cooling system of any one of configurations(35) through (38), wherein the at least one hardware element comprises aD-ring attached to an external surface of the container.(40) The two-phase immersion cooling system of any one of configurations(35) through (38), further comprising at least one pressure-releasevalve located within 10 cm from an edge of the first wall andfluidically coupled to the volume such that the gas can be released fromthe volume when pressure within the volume exceeds a threshold value.(41) The two-phase immersion cooling system of configuration (40),wherein a pressure-release valve of the at least one pressure-releasevalve is located within 10 cm of a top edge of the container such that,when the bellows assembly is in use in the two-phase immersion coolingsystem, the gas released from the volume contains a lower percentage ofcoolant-liquid vapor from coolant liquid used when the two-phaseimmersion cooling system is in operation than if the pressure-releasevalve of the at least one pressure-release valve were located at a lowerelevation on the first wall.(42) The two-phase immersion cooling system of any one of configurations(35) through (41), further comprising: at least one pressure-releasevalve fluidically coupled to the volume such that the gas can bereleased from the volume when pressure within the volume exceeds athreshold value; and a vapor barrier arranged to transmit air to thepressure-release valve and to block passage of coolant-liquid vapor fromcoolant liquid used when the two-phase immersion cooling system is inoperation.(43) The two-phase immersion cooling system of any one of configurations(35) through (42), further comprising at least one isolation valvearranged to isolate the air space in the tank from the second volume.(44) The two-phase immersion cooling system of configuration (43),further comprising: an access door on the tank to access an interiorregion of the tank; a sensor to detect opening of the access door; and acontroller to receive a signal from the sensor indicating the opening ofthe access door and issue a command signal to activate the at least oneisolation valve in response to receiving the signal, wherein activationof the at least one isolation valve isolates the air space in the tankfrom the second volume.(45) The two-phase immersion cooling system of any one of configurations(35) through (44), wherein the first wall and second wall deform awayfrom and toward each other in directions that are approximatelyhorizontal, when the bellows assembly is in use in the two-phaseimmersion cooling system.(46) The two-phase immersion cooling system of any one of configurations(35) through (45), wherein the first wall and second wall deform awayfrom and toward each other in directions that are approximatelyvertical, when the bellows assembly is in use in the two-phase immersioncooling system.(47) The two-phase immersion cooling system of any one of configurations(35) through (46) in a combination with a heater arranged to provideheat to the gas within the volume such that coolant-liquid vaporcontained within the volume does not condense when the bellows assemblyis in use in the two-phase immersion cooling system.(48) The two-phase immersion cooling system of configuration (47),wherein the heater comprises an electrical heating element thermallycoupled to the bellows assembly.(49) The two-phase immersion cooling system of configuration (47),wherein the heater comprises a conduit to carry a heated liquid into andout of the container.(50) The two-phase immersion cooling system of any one of configurations(35) through (49), wherein at least a portion of one wall of thecontainer is thermally coupled to a wall of the tank.(51) The two-phase immersion cooling system of any one of configurations(35) through (50), further including insulation arranged to thermallyinsulate at least a portion of the container from an externalenvironment.(52) The two-phase immersion cooling system of any one of configurations(35) through (51), wherein at least one of the first wall, the secondwall, and the third wall comprises thermal insulation.(53) The two-phase immersion cooling system of any one of configurations(35) through (52), including a vapor barrier fluidically coupled to thevolume to capture at least one gaseous component within the gas.(54) The two-phase immersion cooling system of configuration (53),wherein the vapor barrier is an adsorbing filter or desiccant arrangedto capture one or both of coolant-liquid vapor and water vapor from thegas admitted into the volume.(55) The two-phase immersion cooling system of configuration (54),wherein the vapor barrier is an activated filter to capturecoolant-liquid vapor from coolant liquid used when the two-phaseimmersion cooling system is in operation.(56) The two-phase immersion cooling system of any one of configurations(35) through (55), wherein a thickness of the first wall between 100microns and 3 millimeters.(57) The two-phase immersion cooling system of any one of configurations(35) through (56), wherein the polymer comprises polyurethane.(58) The two-phase immersion cooling system of any one of configurations(35) through (57), wherein the first wall and the second wall have asame rectangular shape.(59) The two-phase immersion cooling system of any one of configurations(35) through (58), wherein an area of the first surface is greater than0.2 m².(60) A method of cooling semiconductor dies in a tank of a two-phaseimmersion cooling system, the method comprising: receiving heat from thesemiconductor dies into a coolant liquid within the tank, the coolantliquid filling a portion of the tank below an air space occupying a topregion of the tank; receiving gas from the air space into a volumeenclosed by a container of a bellows assembly in response to an increasein pressure of the gas, wherein the bellows assembly includes a portfluidically coupled to the air space and the container has a firstsurface spanning a first surface area that encloses the volume;deforming a first wall of the container in a first direction to increasethe volume while receiving the gas, wherein the first wall comprises apolymer and has a second surface spanning a second surface area;expelling the gas from the volume in response to a decrease in pressureof the gas; and deforming the first wall of the container in a seconddirection opposite the first direction to decrease the volume whileexpelling the gas, wherein: the container includes a second wall havinga third surface spanning a third surface area, the second wall beingseparated from the first wall by at least a portion of the volume andoriented approximately parallel to the first wall when the volume is notunder pressure or vacuum, the second surface area and the third surfacearea comprise a majority of the first surface area, the containerfurther includes a third wall extending between and connected to thefirst wall and the second wall, and the bellows assembly furtherincludes at least one hardware element attached to at least one of thefirst wall, the second wall, and the third wall to mount the containerin an orientation such that at least one of the first wall and thesecond wall deforms or deform outward from a center of the containerwithout external hinderance when the volume is under pressure anddeforms or deform inward without external hinderance when the volume isunder vacuum.(61) The method of (60), wherein the second wall and the third wall alsocomprise the polymer.(62) The method of (60) or (61), further comprising directing the gasreceived into the volume such that the gas flows into the container in adirection that is not normal to the first surface of the first wall andnot normal to the second surface of the second wall.(63) The method of any one of (60) through (62), further comprisingreleasing, with a pressure-release valve, gas from the volume into anambient atmosphere outside the container when pressure of the gas in thevolume exceeds a threshold value, wherein the pressure-release valve islocated is located within 10 cm of a top edge of the container such thatthe gas released from the volume contains a lower percentage ofcoolant-liquid vapor from coolant liquid used in the two-phase immersioncooling system than if the pressure-release valve were located at alower elevation on the container.(64) The method of (63), further comprising: blocking passage of thecoolant-liquid vapor to the pressure-release valve with a vapor barrier;and transmitting air molecules through the vapor barrier to thepressure-release valve.(65) The method of any one of (60) through (64), wherein the first walland second wall deform away from each other and toward each other indirections that are approximately horizontal when receiving the gas intothe volume and when expelling the gas from the volume, respectively.(66) The method of any one of (60) through (65), wherein the first walland second wall deform away from each other and toward each other indirections that are approximately vertical when receiving the gas intothe volume and when expelling the gas from the volume, respectively.(67) The method of any one of (60) through (66), further comprising:providing heat to the gas within the volume such that coolant-liquidvapor contained within the volume does not condense when the bellowsassembly is in use in the two-phase immersion cooling system.(68) The method of (67), further comprising: providing the heat with anelectrical heating element thermally coupled to the bellows assembly.(69) The method of (60) through (68), further comprising: providing theheat with a conduit carrying a heated liquid into and out of thecontainer.(70) The method of any one of (60) through (69), further comprisingretaining heat in the container with insulation arranged to thermallyinsulate at least a portion of the container from an externalenvironment.(71) The method of any one of (60) through (70), further comprisingcapturing, with a vapor barrier fluidically coupled to the volume, atleast one gaseous component within the gas.(72) The method of any one of (60) through (71), further comprising:detecting, with a sensor, access to the air space; and automaticallyisolating the volume from the air space with at least one isolationvalve in response to receiving a signal from the sensor indicating theaccess to the air space.

CONCLUSION

While various inventive embodiments have been described and illustratedherein, those of ordinary skill in the art will readily envision avariety of other means and/or structures for performing the functionand/or obtaining the results and/or one or more of the advantagesdescribed herein, and each of such variations and/or modifications isdeemed to be within the scope of the inventive embodiments describedherein. More generally, those skilled in the art will readily appreciatethat all parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the inventive teachingsis/are used. Those skilled in the art will recognize or be able toascertain, using no more than routine experimentation, many equivalentsto the specific inventive embodiments described herein. It is,therefore, to be understood that the foregoing embodiments are presentedby way of example only and that inventive embodiments may be practicedotherwise than as specifically described. Inventive embodiments of thepresent disclosure are directed to each individual feature, system,article, material, kit, and/or method described herein. In addition, anycombination of two or more such features, systems, articles, materials,kits, and/or methods, if such features, systems, articles, materials,kits, and/or methods are not mutually inconsistent, is included withinthe inventive scope of the present disclosure.

Also, various inventive concepts may be embodied as one or more methods,of which an example has been provided. The acts performed as part of themethod may be ordered in any suitable way. Accordingly, embodiments maybe constructed in which acts are performed in an order different thanillustrated, which may include performing some acts simultaneously, eventhough shown as sequential acts in illustrative embodiments.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

Unless stated otherwise, the terms “approximately” and “about” are usedto mean within ±20% of a target (e.g., dimension or orientation) in someembodiments, within ±10% of a target in some embodiments, within ±5% ofa target in some embodiments, and yet within ±2% of a target in someembodiments. The terms “approximately” and “about” can include thetarget. The term “essentially” is used to mean within ±3% of a target.

The indefinite articles “a” and “an,” as used herein, unless clearlyindicated to the contrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein, should be understood to mean“either or both” of the elements so conjoined, i.e., elements that areconjunctively present in some cases and disjunctively present in othercases. Multiple elements listed with “and/or” should be construed in thesame fashion, i.e., “one or more” of the elements so conjoined. Otherelements may optionally be present other than the elements specificallyidentified by the “and/or” clause, whether related or unrelated to thoseelements specifically identified. Thus, as a non-limiting example, areference to “A and/or B”, when used in conjunction with open-endedlanguage such as “comprising” can refer, in one embodiment, to A only(optionally including elements other than B); in another embodiment, toB only (optionally including elements other than A); in yet anotherembodiment, to both A and B (optionally including other elements); etc.

As used herein, “or” should be understood to have the same meaning as“and/or” as defined above. For example, when separating items in a list,“or” or “and/or” shall be interpreted as being inclusive, i.e., theinclusion of at least one, but also including more than one, of a numberor list of elements, and, optionally, additional unlisted items. Onlyterms clearly indicated to the contrary, such as “only one of” or“exactly one of” or “consisting of,” will refer to the inclusion ofexactly one element of a number or list of elements. In general, theterm “or” as used herein shall only be interpreted as indicatingexclusive alternatives (i.e., “one or the other but not both”) whenpreceded by terms of exclusivity, such as “either,” “one of,” “only oneof,” or “exactly one of.” “Consisting essentially of,” shall have itsordinary meaning as used in the field of patent law.

As used herein, the phrase “at least one,” in reference to a list of oneor more elements, should be understood to mean at least one elementselected from any one or more of the elements in the list of elements,but not necessarily including at least one of each and every elementspecifically listed within the list of elements and not excluding anycombinations of elements in the list of elements. This definition alsoallows that elements may optionally be present other than the elementsspecifically identified within the list of elements to which the phrase“at least one” refers, whether related or unrelated to those elementsspecifically identified. Thus, as a non-limiting example, “at least oneof A and B” (or, equivalently, “at least one of A or B,” or,equivalently “at least one of A and/or B”) can refer, in one embodiment,to at least one, optionally including more than one, A, with no Bpresent (and optionally including elements other than B); in anotherembodiment, to at least one, optionally including more than one, B, withno A present (and optionally including elements other than A); in yetanother embodiment, to at least one, optionally including more than one,A, and at least one, optionally including more than one, B (andoptionally including other elements); etc.

In the specification above, all transitional phrases such as“comprising,” “including,” “carrying,” “having,” “containing,”“involving,” “holding,” “composed of,” and the like are to be understoodto be open-ended, i.e., to mean including but not limited to. Only thetransitional phrases “consisting of” and “consisting essentially of”shall be closed or semi-closed transitional phrases, respectively, asset forth in the United States Patent Office Manual of Patent ExaminingProcedures, Section 2111.03.

What is claimed is:
 1. A two-phase immersion cooling system comprising:a tank to contain one or more printed circuit boards havingsemiconductor dies to be cooled during operation of the semiconductordies; and a bellows assembly fluidically coupled to an air space withinthe tank and forming a normally-closed first volume that includes theair space, the bellows assembly comprising: a container comprising apolymer and enclosing a second volume that is a portion of the firstvolume, the container having a first surface spanning a first surfacearea that encloses the second volume, wherein at least a portion of thecontainer is reversibly deformable to increase and decrease an amount ofthe second volume enclosed by the container; a first wall comprising thepolymer and having a second surface spanning a second surface area; asecond wall having a third surface spanning a third surface area, thesecond wall separated from the first wall by at least a portion of thesecond volume and oriented approximately parallel to the first wall whenthe first volume is not under pressure or vacuum, wherein the secondsurface area and the third surface area comprise a majority of the firstsurface area; a third wall extending between and connected to the firstwall and the second wall; at least one port in the third wall to admitgas into the second volume from the air space when the first volume isunder pressure and expel the gas from the second volume into the airspace when the first volume is under vacuum; and at least one hardwareelement attached to at least one of the first wall, the second wall, andthe third wall to mount the container in an orientation such that atleast one of the first wall and the second wall deforms or deformoutward from a center of the container without external hinderance whenthe first volume is under pressure and deforms or deform inward withoutexternal hinderance when the first volume is under vacuum.
 2. Thetwo-phase immersion cooling system of claim 1, wherein the second walland the third wall also comprise the polymer.
 3. The two-phase immersioncooling system of claim 1, wherein a port of the at least one portincludes a port insert comprising: a flange that attaches to the thirdwall; a gasket; and a conduit passing through the third wall and sealedto the third wall with the flange and the gasket.
 4. The two-phaseimmersion cooling system of claim 3, wherein the conduit includes one ormore holes along a length of the conduit located inside the containerand the one or more holes are oriented such that gas flows into thecontainer in a direction that is not normal to the first surface of thefirst wall and not normal to the second surface of the second wall. 5.The two-phase immersion cooling system of claim 1, wherein the at leastone hardware element comprises a D-ring attached to an external surfaceof the container.
 6. The two-phase immersion cooling system of claim 1,further comprising: coolant liquid within the tank that immerses the oneor more printed circuit boards, wherein the air space within the tank islocated above the coolant liquid.
 7. The two-phase immersion coolingsystem of claim 1, further comprising at least one pressure-releasevalve located within 10 cm from an edge of the first wall andfluidically coupled to the volume such that the gas can be released fromthe volume when pressure within the volume exceeds a threshold value. 8.The two-phase immersion cooling system of claim 7, wherein apressure-release valve of the at least one pressure-release valve islocated within 10 cm of a top edge of the container such that, when thebellows assembly is in use in the two-phase immersion cooling system,the gas released from the volume contains a lower percentage ofcoolant-liquid vapor from coolant liquid used when the two-phaseimmersion cooling system is in operation than if the pressure-releasevalve of the at least one pressure-release valve were located at a lowerelevation on the first wall.
 9. The two-phase immersion cooling systemof claim 1, further comprising: at least one pressure-release valvefluidically coupled to the volume such that the gas can be released fromthe volume when pressure within the volume exceeds a threshold value;and a vapor barrier arranged to transmit air to the pressure-releasevalve and to block passage of coolant-liquid vapor from coolant liquidused when the two-phase immersion cooling system is in operation. 10.The two-phase immersion cooling system of claim 1, further comprising:at least one isolation valve arranged to isolate the air space in thetank from the second volume.
 11. The two-phase immersion cooling systemof claim 10, further comprising: an access door on the tank to access aninterior region of the tank; a sensor to detect opening of the accessdoor; and a controller to receive a signal from the sensor indicatingthe opening of the access door and issue a command signal to activatethe at least one isolation valve in response to receiving the signal,wherein activation of the at least one isolation valve isolates the airspace in the tank from the second volume.
 12. The two-phase immersioncooling system of claim 1, wherein the first wall and second wall deformaway from and toward each other in directions that are approximatelyhorizontal, when the bellows assembly is in use in the two-phaseimmersion cooling system.
 13. The two-phase immersion cooling system ofclaim 1, wherein the first wall and second wall deform away from andtoward each other in directions that are approximately vertical, whenthe bellows assembly is in use in the two-phase immersion coolingsystem.
 14. The two-phase immersion cooling system of claim 1 in acombination with a heater arranged to provide heat to the gas within thevolume such that coolant-liquid vapor contained within the volume doesnot condense when the bellows assembly is in use in the two-phaseimmersion cooling system.
 15. The two-phase immersion cooling system ofclaim 14, wherein the heater comprises an electrical heating elementthermally coupled to the bellows assembly.
 16. The two-phase immersioncooling system of claim 14, wherein the heater comprises a conduit tocarry a heated liquid into and out of the container.
 17. The two-phaseimmersion cooling system of claim 1, wherein at least a portion of onewall of the container is thermally coupled to a wall of the tank. 18.The two-phase immersion cooling system of claim 1, further includinginsulation arranged to thermally insulate at least a portion of thecontainer from an external environment.
 19. The two-phase immersioncooling system of claim 1, wherein at least one of the first wall, thesecond wall, and the third wall comprises thermal insulation.
 20. Thetwo-phase immersion cooling system of claim 1, including a vapor barrierfluidically coupled to the volume to capture at least one gaseouscomponent within the gas.
 21. The two-phase immersion cooling system ofclaim 20, wherein the vapor barrier is an adsorbing filter or desiccantarranged to capture one or both of coolant-liquid vapor and water vaporfrom the gas admitted into the volume.
 22. The two-phase immersioncooling system of claim 20, wherein the vapor barrier is an activatedfilter to capture coolant-liquid vapor from coolant liquid used when thetwo-phase immersion cooling system is in operation.
 23. The two-phaseimmersion cooling system of claim 1, wherein a thickness of the firstwall between 100 microns and 3 millimeters.
 24. The two-phase immersioncooling system of claim 1, wherein the polymer comprises polyurethane.25. The two-phase immersion cooling system of claim 1, wherein thepolymer comprises mylar.
 26. The two-phase immersion cooling system ofclaim 1, wherein the polymer comprises polyethylene.
 27. The two-phaseimmersion cooling system of claim 1, wherein the polymer comprisessilicone.
 28. The two-phase immersion cooling system of claim 1, whereinthe first wall and the second wall have a same rectangular shape. 29.The two-phase immersion cooling system of claim 1, wherein an area ofthe first surface is greater than 0.2 m².